PROJECT SUMMARY/ABSTRACT The chemotherapy decision-making process in older women with early-stage breast cancer is complex. Although older women derive a similar degree of benefit from chemotherapy as compared to their younger counter-parts, there are other issues such as medical comorbidities and unique adverse effects that may influence the recommendations of physicians and preferences of patients, subsequently impacting treatment outcomes. Currently, there are no decision aids available to guide patients in considering tradeoffs between quality of life and prognosis conferred by their disease and treatment. The literature supports that older patients desire more active roles in decision-making, and a critical need exists for tools to facilitate patient- centered communication and shared decision-making. Evidence supports that decision aids enhance shared- decision making processes. In the proposed project, I will develop a decision aid to meet the information and clinical needs of older adult women making breast-cancer treatment decisions, and support their physician in navigating this conversation. The tool will include two components: (1) a physician-facing component that will incorporate validated breast-cancer risk outcomes, and (2) a patient-facing component that will include an include education (overview of the disease, goals of therapy), description of benefits/risks of treatment, feedback on tailored outcome probabilities, and values clarification. My overall hypothesis is that a decision support tool will provide patients and physicians with tailored information regarding the risks and benefits of chemotherapy and values clarification to support high quality, shared decisions. An advisory panel composed of patients, oncologists, geriatricians, nurses and patient advocates will provide regular feedback throughout the development process and engage in an iterative process of development. We will subsequently evaluate the tool for acceptability and feasibility through a field test of 20 patients. After incorporating feedback from the field test to create a finalized version of the tool, we will carry out a cluster-randomized pilot study that will include randomization to a usual-care arm with the objective of evaluating the efficacy of the decision support tool by measuring patient-reported outcomes of decisional conflict, knowledge, and a measure of the decision- process/approach. Ultimately, the results of this project will inform a larger randomized control trial to assess whether the decision tool improves patient knowledge, decision quality/processes, and quality of life. Furthermore, through my work on this project and the proposed training activities, I will strengthen by skill-set in decision science, health communication, qualitative/mixed-methods methodology and clinical trial design which allow me to transition to my long-term goal of becoming an established independent investigator.